Fan connecting reinforcing cap to hub

ABSTRACT

A fan having blades secured on arms which project radially from a central hub and reinforcing caps fixedly connected to the blades and arms, said reinforcing caps extending to and fixedly connected to said hub.

United States Patent [191 Strick 111 3,711,219 1 Jan. 16,1973

[541 FAN CONNECTING REINFORCING CAP TO HUB {75] Inventor: Karl H. Strick, Chatham, Ontario,

Canada [73] Assignee: Fram Corporation, East Providence,

[22] Filed: Sept. 20, 1971 [21] Appl. No.: 181,664

[52] US. Cl. ..4l6/132, 416/240, 416/210 [51] Int. Cl ..FO4d 29/38 [58] Field of Search...4l6/l32, 214,132 A, 240, 210

[56] References Cited UNITED STATES PATENTS 1,246,65ETi 13TT Glantiberg ..416/2l 0 UX 2,395,193 2/1946 Place ..4l6/l32 UX 3,044,557 7/1962 Posh ..416/l32 3,406,760 10/1968 Weir ..4l6/l32 3,594,098 7/1971 Pratinidhi r ..4l6/l32 3,679,321 7/1972 Strick 416/132 Primary Examiner-Everette A. Powell, Jr. AttorneyCharles C. Winchester [57] ABSTRACT A fan having blades secured on arms which project radially from a central hub and reinforcing caps fixedly connected to the blades and arms, said reinforcing caps extending to and fixedly connected to said hub.

24 Claims, 7 Drawing Figures 1 FAN CONNECTING REINFORCING CAP TO HUB This invention relates to fans and more particularly to fans used for automotive cooling.

It is a principal object of this invention to provide a fan of inherently strengthened design which may therefore be lighter and less costly for a given application. To achieve this object it is accordingly another object to strengthen and at the same time lighten the arms of the fan and to lighten the reinforcing cap without weakening the structure supporting the fan blades. It is still another object of a preferred embodiment to eliminate the need for prepainting the fan arms and thereby to reduce production costs.

In general the invention features a blade on one side of each fan arm, a reinforcing cap fixedly connected by arm fastening members against the side of each blade opposite the associated arm and the extension of each reinforcing cap inwardly to the hub of the fan, each cap also being fixedly connected by a hub fastening member to the hub.

In preferred embodiments, the invention additionally features positioning the blades on the downstream sides of the arms and the reinforcing caps on the downstream sides of the blades; the securement of the reinforcing caps to the hub in a second plane downstream ofa first plane defined at the position of joinder of the hub and the arms; a bead along the leading edge of the reinforcing caps; flexible fan blades and a leg of the reinforcing caps between the arms and blades preventing contact therebetween; ribs in the arms and hub; and the extension of the caps to the second plane to define a space between the caps at the junction of the arms to the hub.

Other objects, features and advantages of the invention will be apparent to those skilled in the art from the following detailed description of a preferred embodiment thereof taken together with the accompanying drawings in which: I

FIG. 1 is a plan view of the upstream side of an engine cooling fan embodying the invention;

FIG. 2 is an enlarged end view of an arm, blade and associated structure taken along the line 22 of FIG.

FIG. 3 is a reduced plan view of the downstream side of the arm, blade and associated structure taken along the line 33 of FIG. 2; and

FIGS. 4, 5, 6 and 7 are enlarged sectional views taken, respectively, along the lines 44, 5-5, 6-6 and 7-7 of FIG. 1.

As shown in FIGS. 1 and 2, the fan 10 comprises, generally, a central hub 12, arms 24 integral with the hub and projecting radially therefrom, blades 32 on one side of the arms, reinforcing caps 36 wrapped about the leading edges of the blades, and arm fastening members in the form of rivets 40 fixedly connecting the blades and reinforcing caps to the arms.

The arms 24 are asymmetrically positioned about the hub 12 and are arranged for balance of the fan, the arcuate distances between radial reference lines at the arms (drawn parallel to the leading and trailing edges of the arms and the attached blades, respectively) being shown in FIG. 1. The root 26 of each arm intermediate the hub 12 and the blade 32 is twisted as shown in FIGS. 2, 4, 5, 6 and 7, so that the plane of each arm throughout its major extent, between root26 and the outer tip 31 of blade 32, is at a 25 angle to the plane of fan rotation, i.e., the plane of the hub mounting face 14, where the blade is attached thereto. Outwardly spaced from the root 26, each arm transversely comprises a planar leading portion 27 and, a trailing portion 28 curved toward the upstream side of the fan, i.e., convexly as viewed from the downstream side. The hub and arms are formed of relatively rigid steel (SAE 950 AK steel, 0.120 inch thick).

Positioned on the downstream side of each arm is a blade 32 curved, transversely between the leading edge 33 and trailing edge 35 thereof, away from the plane of arm 24, i.e., with the convex side of the blade adjacent the downstream side of the arm, best shown in FIG. 2. The blade is formed of a resilient, flexible steel (AISI 301 stainless steel, 0.015 inch thick) and defines an air moving surface extending a substantial distance behind the trailing portion 28 of the arm 24. The chord angle between the arm leading edge at 27 and the blade trailing edge 35 is about 45. The mutual configuration of the arm trailing portion 28 and the blade 32 thereat provides a separation thereof at a generally acute angle as shown in FIG. 2. Provided at the trailing edge 35 of each blade is a weight 34 comprising an integral portion of blade 32 folded back upon itself to engage the convex side of the blade, as shown and described in US. Pat. No. 3,594,098, issued July 20, 1971.

Reinforcing cap 36 comprises in section two generally parallel legs 37, 39, connected by a tubular bead 38 along the leading edge thereof. The cap is constructed of light gage steel (SAE 950 A, cold rolled prepainted steel, 0.020 inch thick). The reinforcing cap is located on the downstream side of arm 24 and sandwiches the leading portion and edge 33 of blade 32 therein between legs 37 and 39 as shown in FIG. 2. Bead 38 is symmetrically arranged relative to legs 37, 39 and as shown in FIG. 3 extends radially the length of arm 24. The bead 38 is accommodated in a corresponding concave groove or rib 30 on the downstream side of arm 24 extending radially the length of the arm and terminating at the inner end of the arm at hub 12. The leg 39 on the upstream side of blade 32 conforms transversely to the shape of the downstream side of arm 24 particularly the curved trailing portion 28 thereof, extending slightly therebehind along the radial extent thereat of blade 32. The downstream leg 37 extends transversely only a limited distance toward the trailing edge of arm 24, to the point at which the curvature of the trailing portion 28 commences, to avoidinterference with blade 32 in operation of the fan. The cap extends radially outward along about 85 percent of the radial length of blade 32 whereas the arm extends along only about percent of the radial length of the blade.

Rivets 40 extending through arm 24, blade .32 and both legs 37, 39 of cap 36, and bearing on the upstream side of arm 24 and the downstream side of leg 37, fixedly connect blade and cap to arm 24.

The fan hub 12 comprises a planar mounting face 14 having a central pilot hole 16 and symmetrically disposed mounting holes 18 therethrough. Mounting face 14 is in the same first plane as arms 24 .at the point of joinder of the root 26 thereof with hub 12, best shown in FIG. 7. About mounting face 14, an annular groove 22 is formed to provide an annular rib 23 in a second plane axially spaced downstreamof the mounting face 14 and the first plane. To strengthen the hub 12, symmetrically disposed in the mounting face 14, between mounting holes 18, are a number of ribs or projections 20 extending to a third plane upstream of the mounting face 14 and the first plane.

As seen in FIGS. 4-7, cap 36 extends inwardly of the periphery of hub 12 and is fixedly connected by hub connecting member, rivet 42, through legs 37, 39 to rib 23 in the second plane downstream of the plane of mounting face 14 and arm 24. The bead 38 ends at the edge of rib 23 and the legs 37, 39 are joined by a simple fold at the rib 23. Cap 36 extends in a straight line inwardly from adjacent blade 32 and the innermost of rivets 40, which is spaced radially outwardly from hub 12, contacting arm 24 at the outer portions of root 26, FIGS. 4, and 7, but, as the root 26 reaches the plane of its joinder to hub 12, FIGS. 6 and 7, the cap becomes axially spaced from root 26 as the cap continues in a straight line inwardly and downstream to rib 23.

In operation, as the fan rotates clockwise, indicated by the arrow in FIG. 1, air is moved from upstream to downstream by the blades 32 as indicated by arrows in FIG. 2. As air speed increases, air pressure and centrifugal force cause the blades 32 to decamber--in general, to move toward the plane of the hub 12, as indicated by the arrow adjacent the trailing portion of the blade in FIG. 2. Decambering of the blade is limited by the curved trailing portion 28 of arm 24 and the abutting leg 39 of cap 36.

The operation of the fan imposes bending and centrifugal stresses on the arms 24 which are at their highest level at the root 26 particularly where joined to the hub 12. The bending stresses tend to bend the arms toward the upstream side of the fan. The connection of the reinforcing cap 26 between the hub and the arms of the fan, the connection of the cap to the hub in a plane spaced from the plane of the arms, the positioning of the blades and caps on the downstream side of the arms, the provision of a gap between the cap and the arms at the joinder of the arms to the hub and the provision of a radially extending bead 38 on the cap and a cooperating rib 30 in the arms, strengthen the arms to resist the bending and centrifugal stresses.

One result of such strengthening is that lighter weight materials may be employed, in the hub and arms for a given application, than heretofore deemed practical. Additionally, the reinforcing cap may be of lighter materials than heretofore employed since the upstream legs 39, against which blade 32 decambers, is supported by arm 24. Thus, for a given application, materials costs may be lowered and a weight reduction achieved, a particularly important feature in automotive fans which are typically mounted in cantilever fashion on a water pump shaft and the weight of which affects the life of the water pump shaft and bearings. Finally the extension of the upstream leg 39 of prepainted cap 36 beyond the trailing edge of the arm 24 eliminates the necessity for prepainting the arms which is otherwise required if the blades 32 are able to contact the arms, thus achieving further production cost savings.

Other embodiments will occur to those skilled in the art from the foregoing non-limiting description of a preferred embodiment of the invention.

What is claimed is:

1. In a fan comprising a hub, a plurality of arms in tegral with said hub and projecting outwardly therefrom, a blade positioned against one side of each of said arms, a reinforcing cap positioned against each said blade on the side thereof opposite the arm against which said blade is positioned, each said blade thereby positioned between an overlying cap and an arm, and arm fastening members radially spaced from said hub fixedly connecting each said blade and cap to an arm, that improvement in which each said reinforcing cap extends radially inwardly to said hub and hub fastening members are provided inwardly of the periphery of said hub fixedly connecting each of said reinforcing caps to said hub.

2. The improvement claimed in claim 1 in which said arms join and extend outwardly from said hub in a first plane and second reinforcing caps are axially spaced from said arms in a second plane at the position thereof at which said arms join said hub.

3. The improvement claimed in claim 2 in which said hub extends to a second plane axially spaced from said first plane and said hub fastening members connect said reinforcing caps to said hub in said second plane.

4. The improvement claimed in claim 1 in which said blades and said reinforcing caps are positioned on the downstream side of said arms, said arms join and extend outwardly from said hub in a first plane, said hub extends to a second plane downstream of said first plane, and said reinforcing caps extend from said blades inwardly and downstream toward and are connected to said hub in said second plane.

5. The improvement claimed in claim 4 in which said reinforcing caps are spaced from said arms and said hub at the position thereof at which said arms join said hub in said first plane.

6. The improvement claimed in claim 4 in which said hub has a central mounting face in said first plane and an annular rib about said mounting face, inwardly of said arms, said rib projecting said hub thereat downstream and defining on the downstream side thereof said second plane, said hub fastening members connecting said reinforcing caps in said second plane to the downstream side of said annular rib.

7. The improvement claimed in claim 6 in which said reinforcing caps extend in a straight line from adjacent the inner most arm fastening member on each said arm to said annular rib in said second plane and are thereby spaced from said arms and said hub at the position thereof at which said arms join said hub in said first plane.

8. The improvement claimed in claim 7 in which strengthening ribs are disposed in said mounting face projecting therefrom to a third plane upstream of said first plane.

9. The improvement claimed in claim 1 in which said reinforcing caps each comprise a pair of closely spaced legs sandwiching the leading portions of said blades therebetween, said legs connected by a tubular bead in said reinforcing cap, said bead extending radially and connecting said legs from adjacent said hub outwardly along said leading portion of said blade.

10. The improvement claimed in claim 9 in which a radially extending concave rib is provided on the side of each said arm adjacent said reinforcing cap, said concave rib extending from said hub outwardly therealong and said beads are positioned in and against said ribs.

11. The improvement claimed in claim in which said ribs in said arms extend the entire length of said arms, and said reinforcing caps, including said beads, extend radially beyond the ends of said arms.

12. The improvement claimed in claim 9 in which said blades and said reinforcing caps are positioned on the downstream side of said arms, said arms join and extend outwardly from said hub in a first plane, said hub extends to a second plane downstream of said first plane, and said reinforcing caps extend from said blades inwardly and downstream toward and are connected to said hub in said second plane.

13. The improvement claimed in claim 12 in which said reinforcing caps are spaced from said arms and said hub at the position thereof at which said arms join said hub in said first plane.

14. The improvement claimed in claim 12 in which said hub has a central mounting face in said first plane and an annular rib about said mounting face, inwardly of said arms, said rib projecting said hub thereat downstream and defining on the downstream side thereof said second plane, said hub fastening members connecting said reinforcing caps in said second plane to the downstream side of said annular rib.

15. The improvement claimed in claim 14 in which said reinforcing caps and said beads thereof extend in a straight line from adjacent the innermost arm fastening member on each side arm to said annular rib in said second plane and are thereby spaced from said arms and said hub at the position thereof at which said arms join said hub in said first plane.

16. The improvement claimed in claim 15 in which a radially extending concave rib is provided on the downstream side of each said arm extending from said hub outwardly therealong and said beads are positioned in and against said ribs.

17. The improvement claimed in claim 16 in which said ribs in said arms extend the entire length of said arms, and said reinforcing caps, including said beads extend radially beyond the ends of said arms.

18. The improvement claimed in claim 17 in which said blades each comprise a flexible, resilient member, extending transversely to a position trailing said arms, which decambers toward the upstream side of said fan as rotational speed increases, and the legs of said reinforcing caps on the upstream sides of said blades extending transversely from the leading edges of said blades to the trailing edges of said arms thereby preventing contact between said arms and said blades.

19. The improvement claimed in claim 1 in which said blades and said reinforcing caps are positioned on the downstream side of said arms, said blades each comprise a flexible, resilient member, extending transversely to a position trailing said arms, which decambers toward the upstream side of said fan as rotational speed increases, and in which said reinforcing caps each comprise a pair of closely spaced legs sandwiching the leading portions of said blades therebetween, said legs integrally connected at the leading edges of said reinforcing caps and the legs of said reinforcing caps on the upstream sides of said blades extending transversely from the leading edges of said blades to the trailing edges of said arms. I

0. The improvement claimed in claim 19 in which said arms join and extend outwardly from said hub in a first plane, said hub extends to a second plane downstream of said first plane, and said reinforcing caps extend from said blades inwardly and downstream toward and are connected to said hub in said second plane.

21. The improvement claimed in claim 20 in which said hub has a central mounting face in said first plane and an annular rib about said mounting face, inwardly of said arms, said rib projecting said hub thereat downstream and defining on the downstream side thereof said second plane, said hub fastening members connecting said reinforcing caps in said second plane to the downstream side of said annular rib.

22. The improvement claimed in claim 19 in which said legs are connected at said leading edges of each said reinforcing cap by a bead in said reinforcing cap, said bead extending radially and connecting said legs from said hub outwardly along said leading portion of said blade.

23. The improvement claimed in claim 22 in which said reinforcing caps and said beads thereof extend in a straight line from adjacent the innermost arm fastening member on each said arm to said annular rib in said second plane and are thereby spaced from said arms and said hub at the position thereof at which said arms join said hub in said first plane.

24. The improvement claimed in claim 23 in which a radially extending concave rib is provided on the downstream side of each said arm extending from said hub outwardly therealong and said beads are positioned in and against said ribs. 

1. In a fan comprising a hub, a plurality of arms integral with said hub and projecting outwardly therefrom, a blade positioned against one side of each of said arms, a reinforcing cap positioned against each said blade on the side thereof opposite the arm against which said blade is positioned, each said blade thereby positioned between an overlying cap and an arm, and arm fastening members radially spaced from said hub fixedly connecting each said blade and cap to an arm, that improvement in which each said reinforcing cap extends radially inwardly to said hub and hub fastening members are provided inwardly of the periphery of said hub fixedly connecting each of said reinforcing caps to said hub.
 2. The improvement claimed in claim 1 in which said arms join and extend outwardly from said hub in a first plane and second reinforcing caps are axially spaced from said arms in a second plane at the position thereof at which said arms join said hub.
 3. The improvement claimed in claim 2 in which said hub extends to a second plane axially spaced from said first plane and said hub fastening members connect said reinforcing caps to said hub in said second plane.
 4. The improvement claimed in claim 1 in which said blades and said reinforcing caps are positioned on the downstream side of said arms, said arms join and extend outwardly from said hub in a first plane, said hub extends to a second plane downstream of said first plane, and said reinforcing caps extend from said blades inwardly and downstream toward and are connected to said hub in said second plane.
 5. The improvement claimed in claim 4 in which said reinforcing caps are spaced from said arms and said hub at the position thereof at which said arms join said hub in said first plane.
 6. The improvement claimed in claim 4 in which said hub has a central mounting face in said first plane and an annular rib about said mounting face, inwardly of said arms, said rib projecting said hub thereat downstream and defining on the downstream side thereof said second plane, said hub fastening members connecting said reinforcing caps in said second plane to the downstream side of said annular rib.
 7. The improvement claimed in claim 6 in which said reinforcing caps extend in a straight line from adjacent the inner most arm fastening member on each said arm to said annular rib in said second plane and are thereby spaced from said arms and said hub at the position thereof at which said arms join said hub in said first plane.
 8. The improvement claimed in claim 7 in which strengthening ribs are disposed in said mounting face projecting therefrom to a third plane upstream of said first plane.
 9. The improvement claimed in claim 1 in which said reinforcing caps each comprise a pair of closely spaced legs sandwiching the leading portions of said blades therebetween, said legs connected by a tubular bead in said reinforcing cap, said bead extending radially and connecting said legs from adjacent said hub outwardly along said leading portion of said blade.
 10. The improvement claimed in claim 9 in which a radially extending concave rib is provided on the side of each said arm adjacent said reinforcing cap, said concave rib extending from said hub outwardly therealong and said beads are positioned in and against said ribs.
 11. The improvement claimed in claim 10 in which said ribs in said arms extend the entire length of said arms, and said reinforcing caps, including said beads, extend radially beyond the ends of said arms.
 12. The improvement claimed in claim 9 in which said blades and said reinforcing caps are positioned on the downstream side of said arms, said arms join and extend outwardly from said hub in a first plane, said hub extends to a second plane downstream of said first plane, and said reinforcing caps extend from said blades inwardly and downstream toward and are connected to said hub in said second plane.
 13. The improvement claimed in claim 12 in which said reinforcing caps are spaced from said arms and said hub at the position thereof at which said arms join said hub in said first plane.
 14. The improvement claimed in claim 12 in which said hub has a central mounting face in said first plane and an annular rib about said mounting face, inwardly of said arms, said rib projecting said hub thereat downstream and defining on the downstream side thereof said second plane, said hub fastening members connecting said reinforcing caps in said second plane to the downstream side of said annular rib.
 15. The improvement claimed in claim 14 in which said reinforcing caps and said beads thereof extend in a straight line from adjacent the innermost arm fastening member on each side arm to said annular rib in said second plane and are thereby spaced from said arms and said hub at the position thereof at which said arms join said hub in said first plane.
 16. The improvement claimed in claim 15 in which a radially extending concave rib is provided on the downstream side of each said arm extending from said hub outwardly therealong and said beads are positioned in and agaiNst said ribs.
 17. The improvement claimed in claim 16 in which said ribs in said arms extend the entire length of said arms, and said reinforcing caps, including said beads extend radially beyond the ends of said arms.
 18. The improvement claimed in claim 17 in which said blades each comprise a flexible, resilient member, extending transversely to a position trailing said arms, which decambers toward the upstream side of said fan as rotational speed increases, and the legs of said reinforcing caps on the upstream sides of said blades extending transversely from the leading edges of said blades to the trailing edges of said arms thereby preventing contact between said arms and said blades.
 19. The improvement claimed in claim 1 in which said blades and said reinforcing caps are positioned on the downstream side of said arms, said blades each comprise a flexible, resilient member, extending transversely to a position trailing said arms, which decambers toward the upstream side of said fan as rotational speed increases, and in which said reinforcing caps each comprise a pair of closely spaced legs sandwiching the leading portions of said blades therebetween, said legs integrally connected at the leading edges of said reinforcing caps and the legs of said reinforcing caps on the upstream sides of said blades extending transversely from the leading edges of said blades to the trailing edges of said arms.
 20. The improvement claimed in claim 19 in which said arms join and extend outwardly from said hub in a first plane, said hub extends to a second plane downstream of said first plane, and said reinforcing caps extend from said blades inwardly and downstream toward and are connected to said hub in said second plane.
 21. The improvement claimed in claim 20 in which said hub has a central mounting face in said first plane and an annular rib about said mounting face, inwardly of said arms, said rib projecting said hub thereat downstream and defining on the downstream side thereof said second plane, said hub fastening members connecting said reinforcing caps in said second plane to the downstream side of said annular rib.
 22. The improvement claimed in claim 19 in which said legs are connected at said leading edges of each said reinforcing cap by a bead in said reinforcing cap, said bead extending radially and connecting said legs from said hub outwardly along said leading portion of said blade.
 23. The improvement claimed in claim 22 in which said reinforcing caps and said beads thereof extend in a straight line from adjacent the innermost arm fastening member on each said arm to said annular rib in said second plane and are thereby spaced from said arms and said hub at the position thereof at which said arms join said hub in said first plane.
 24. The improvement claimed in claim 23 in which a radially extending concave rib is provided on the downstream side of each said arm extending from said hub outwardly therealong and said beads are positioned in and against said ribs. 